Dental hand piece



2 Sheets-Sheet 1 J. H. BLAIR DENTAL HAND PIECE Filed DeO. 14, 1937 Jan.30, 1940.

Jan 30, 1940. J. H. BLAIR 2,188,426

DENTAL HAND PIECE Filednec. 14, 1937- 2 sheets-sheet 2 INVENOR.

ATTORNEYS Patented Jan. 30, 1940 UNITED STATES PATENT OFFICE DENTALvHAND PIECE Application December 14, 1937, Serial No. 179,661

- 5 Claims.

This invention relates to dental hand pieces, which are used to hold androtate tools such as burrs and mounted points.

Burrs and mounted points as they are pur- 5 chased by dentists arecustomarily provided with a standard shank. -This Shank is ofcylindrical form, and adjacent to the free end of the shank it isprovided with a segmental recess and a circumferential groove. When theshank is inserted into the conventional dental hand piece, the segmentalrecess makes interlocking engagement with a driving member and thecircumferential groove is engaged by a hook-like latch which holds thetool in place in the hand piece.

In manufacturing the usual dental hand piece and the usual standardshank burrs and mounted points, suiicient tolerance must be allowed toinsure that the hand piece will readily vreceive the burr. Burrs aremade by many manufacturers andare even imported from Europeyand themanufacturers must be sure that the shank of each burr is suicientlysmall to permit its insertion into any of the dental hand pieces in useAby dentists throughout the country. This 25 situation necessitates arelatively large average clearance between the shank of the burr and thesocket of the dental hand piece. Due to this clearance, the burrvibrates considerably in use. This vibration causes the dentist diculty3 in his drilling and grinding operations and greatly adds to thepatients pain. A clean sharp burr running smoothly without any vibrationcauses very little pain to the patient during th average tooth cavityoperation.

Attempts have been made to overcome the foregoing difficulties by meansof special tapered shank burrs, but these are relatively expensive andrequire the dentist to use a special hand piece with which standardshank burrs cannot be used.

The general object of the present invention is to provide a dental handpiece which will receive standard shank burrs and mounted points, andwill hold and operate them without objec- 45 tionable vibration despitethe very considerable manufacturing variations in the size of theShanks.

Another object of the invention is to provide a dental hand piece ofimproved construction which will rmly grip and accurately centercylindrical shank burrs and mounted points.

Of course, dental hand pieces are used in al1 kinds of positions as faras up-side-down and right-side-up are concerned. However, it will beconvenient throughout the specification and claims to refer to thehan-d'piece as being in the position shown in the drawings. It will beunderstood, however, that this is just for convenience in discussing thestructure and has no signicance with respect to the position in which 5:the hand piece may be placed in actual use.

Figure 1 of the drawings is an elevation of a complete hand pieceembodying the present invention.

Figure 2 is a central vertical section showing the driving head with amounted point assembled therewith.

Figure 3 is an enlarged vertical section of a vportion of the structureshown in Figure 2.

Figure 4 is a horizontal section of a portion of the structure, taken ingeneral on the line 4-4 oi Figure 3.

Figure 4a is a vertical vdetail section on the line iai-4a of Figure 4.

Figure 5 is a central vertical section of a toolgripping sleeve which isembodied in the as-y sembly of Figures 2 and -3.

Figure 6 is a plan view of the tool-gripping sleeve shown in Figure 5.

Figure -7 is an elevation of a power-rotated.A sleeve embodied in theassembly of Figures 2 and 3.

Figure 8 is a central verticalv section, showing the tool-grippingsleeve of Figure 5 assembled with respect to the'power-rotated sleeve ofFigure 7.

In Figure 1 there is shown an angular barrel having branches I and II.Branch II terminates in a' head I2 within which is mechanism to hold theshank of, and rotate, a conventional burr or mounted point I4. Thebarrel portions I0 and II are conventional and contain a shaft which isadapted to be rotated by a power connection made at E.

Barrel portion II terminates in a vertical tubular head I in the centerportion of which is located a bearing sleeve I6, secured by a screw I1.Accurately journalled within sleeve I6 is a power-rotated sleevedesignated as a whole by I8. Integral with this sleeve is a gear I9-having vertical teeth which mesh with gear 2D mounted on the end of thedrive shaft 2| contained in barrel portion Il.

Threaded into the lower end of casing I5 is a cap member 22 which may beprovided with an exterior hexagonal formation to receive a wrench.Pressed into the cap 22 is a second bearing sleeve 24 which also makesaccurate t with the powerrotated sleeve I8. It will be apparent that theconstruction thus far described provides for acce curate and adequatemounting of the power-rotated sleeve I8, and that this sleeve is rotatedby power delivered by gear 20.

Within the power-rotated sleeve I8 there is a tool-gripping sleevedesignated as a whole by 25. The ends of the tool-gripping sleeve areformed as tapered (conical) noses 26 and 21 (Fig. 5); and from each endof this sleeve three longitudinal slots 28 extend to make the endportions of the sleeve contractible. The sleeve 25 is also provided withan integral key 29 which enters a slot 30 in power-driven sleeve I3, sothat the tool-gripping sleeve will be rotated in response to rotation ofthe power-driven sleeve. The tapered nose 26 rests upon a tapered(conical) seat 34 (Fig. 8) formed at the bottom of sleeve I8. The top ofsleeve I8 is provided with a hexagonal nut 35 having a tapered (conical)seat |36 which engages the tapered nose 21. Thus, as nut 35 is screwedonto sleeve I8, the tool-gripping sleeve 25 is automatically centeredand the end portions of the tool-gripping sleeve are contracted.

Nut 35 has a hexagonal head 36, and permanently associated with it is acap or wrench member 3l. The cap or wrench member has inwardlyprojecting segmental portions 38 which constitute a wrench formationthat is adapted to engage the wrench faces of the head 36 of the nut. Inassembly, the nut 35 is dropped in from the top to the inside of wrenchmember 31 and then the flange 3S is spun inwardly to prevent removal ofthe nut. Thus assembled, the nut 35 can be screwed onto the sleeve I8,as shown in Figs. 2 and 3; and a spring ring 40 which is positioned inan internal groove in the wrench member 31 frictionally engages theoutside of casing I5. When the parts are in the position shown in Fig.2, the wrench member 31 is frictionally held against rotation by theaction of spring 40, and the head 36 of the nut 35 is free to rotate inthe annular recess 4I. Thus the cap or wrench member 31 acts as aprotective inclosure within which the nut rotates. To loosen or tightennut 35, the wrench member 31 is moved vertically to the position Shownin Fig. 3. Of course, this requires rotational adjustment of the wrenchmember 31 to bring the segmental projections 38 into alignment with thewrench faces of the nut, as shown in. Figs. 3 and 4. Then by turningwrench member 31, the nut 35 is correspondingly turned. To facilitategrasping of the wrench member 31, it is formed with a knurled exteriorsurface, as shown in Fig. 1.

In elevating the wrench member 31 to the position shown in Fig. 3, it isautomatically arrested in the position shown in Fig. 3 by the engagementof circular flange 44 with the corners of the nut. Attention is calledto the fact that in Figs. 2 and 3 the section of the wrench member 31 ison the line A-A of Fig. 4, but the flange 44 extends under the cornersof the nut head 36, as shown in Fig. 4, thereby arresting the upwardmovement of the nut with the segments 38 in wrench engagement with thenut. 'I'he engagement of ange 44 With the corners of the nut head ismore clearly shown in Fig. 4a, which is on line 4a-4a of Fig. 4.

To insert a burr or mounted point into the hand piece, the nut 35 isloosened thereby, allowing the end portions of tool-gripping sleeve 25to expand. The shank 46 of the burr is then inserted, with the segmentalrecess in the shank of the burr in alignment with segmental boss 45,which is integral with the tool-gripping sleeve 25.

'Ihen the nut 35 is tightened, whereupon segmental boss 45 rotativelylocks the shank of the burr to the tool-gripping sleeve, and the twotapered seats 34 and |36 act upon the'tapered noses 26 and 21 of thetool-gripping sleeve to center the same and firmly constrict the endportions of the sleeve about the shank of the burr. Thus the burr isaccurately centered and held against vibration, regardless of largemanufacturing variations in the size of the shank of the burr. 'Iheannular groove 41, which is present in the conventional standard shankbutt, has no function when the burr is mounted in a hand piece of thepresent invention.

In compliance with the patent statutes, I have discussed the best formin which I have contemplated my invention, but it will be understoodthat the disclosure is illustrative and does not limit the scope of theclaims.

What is claimed is:

l. A dental hand piece comprising: a barrel having a free end, a toolhead secured to the free end of the barrel and positioned crosswisethereof, a power driven contractible tool-gripping sleeve within thetool head operable to grip the shank of a tool adjacent to both ends ofthe tool head, the tool projecting from one end of the tool head, andmeans positioned at the opposite end of the tool head to controlcontraction and expansion of the tool-gripping sleeve, said meanscomp-rising a nut rotating with the tool when the same is in use and acap holding the nut captive therein independently of the assembly of thecap and nut on the tool head, the cap having limited axial movementrelative to the nut and the nut and cap having interengaging formationspreventing accidental removal of the cap from the tool head, the caphaving a wrench formation which operatively engages the nut when the capis. in one axial position whereby the cap may be used as a wrench tomanipulate the nut, and the cap also having an annular space in whichthe nut may freely rotate when the cap is in another axial positionwhereby the cap acts as a protective inclosure for the nut when the toolis in use.

2. A dental hand piece comprising: a barrel having a free end, a toolhead secured to the free end of the barrel and positioned crosswisethereof, a power driven contractible tool-gripping sleeve within thetool head operable to grip the shank of a tool adjacent to both ends ofthe tool head, the tool projecting from one end of the tool head, andmeans positioned at the opposite end of the tool head to controlcontraction and expansion of the tool-gripping sleeve, said meanscomprising a nut rotating with the tool when the same is in use and acap holding the nut captive therein independently of the assembly of thecap and nut on the tool head, the cap having limited axial movementrelative to the nut and the nut and cap having interengaging formationspreventing accidental removal of the cap from the tool head, the caphaving an external knurled surface and having an internal wrenchformation' which operatively engages the nut when the cap is in oneaxial position whereby the cap may be used as a wrench to manipulate thenut, and the cap also having an annular space in which the nut mayfreely rotate when the cap is in another axial position whereby the capacts as a protective inclosure for the nut when the tool is in use, andfriction means to prevent accidental rotation of the cap when the nut isrotating in vsaid annular space.` l

3. A dental hand piece comprising: a barrel Ahaving a free end, a toolhead secured to the free end of the barrel and positioned crosswisethereof, a power driven contractible tool-gripping sleeve within thetool head operable to grip the shank of a tool adjacent to both ends ofthe tool head, the tool projecting from one end of the tool head andmeans positioned at the opposite end of the tool head to controlcontraction and expansion of the tool-gripping sleeve, said meanscomprising a nut rotating with the tool when the same is in use and acap holding the nut captive therein independently of the assembly of thecap and nut on the tool head, the cap telescopically engaging the toolhead and having limited axial movement relative to the nut and the nutand cap having interengaging formations preventing accidental removal ofthe cap from the tool head, the cap having a wrench formation whichoperatively engages the nut When the cap is in one axial positionwhereby the cap may be used as a wrench to manipulate the nut, and thecap also having an annular space in which the nut may freely rotate whenthe cap is in another axial position whereby the cap acts as aprotective inclosure for the nut when the tool is in use.

4. A dental hand piece comprising: a barrel having a free end, a toolhead secured to the free end of the barrel and positioned crosswisethereof, a power driven contractible tool-gripping sleeve within thetool head operable to grip the shank of a tool adjacent to both ends ofthe tool head, the tool projecting from one end of the tool head, andmeans positioned at the opposite end of the tool head to controlcontraction and expansion of the tool-gripping sleeve, said meanscomprising a nut rotating with the tool when the same is in use and acap holding the nut captive therein independently of the assembly of thecap and nut on the tool head, the cap telescopically engaging the toolhead and having limited axial movement relative to the nut and the nutand cap having interengaging formations preventing accidental .removalof the cap from the tool head, the cap having an external knurledsurface and having an internal wrench formation which operativelyengages the nut when the cap is in one axial position whereby the capmay be used as a wrench to manipulate the nut, and the cap also havingan annular space in Which the nut may freely rotate when the cap is inanother axial position whereby the cap acts as a protective inclosurefor the nut when the tool is in use, and means to prevent accidentalrotation of the cap when the nut is rotating in said annular space.

5. A dental hand piece comprising: a barrel having a free end, a toolhead secured to the free end of the barre-l and positioned crosswisethereo, a power driven contractible tool-gripping sleeve within the toolhead operable to grip the shank of a tool adjacent to both ends of thetool head, the tool projecting from one end of the tool and'meanspositioned at the opposite end of the tool head to control contractionand expansion of the tool-gripping sleeve, said means axial positionwhereby the cap may be used as' a wrench to manipulate the nut, and thecap also havingv an annular space in which the nut may freely rotatewhen the cap is in another axial position whereby the cap acts as aprotective inclosure for the nut when the tool is in use, and a springring interposed between the cap and the tool head to frictionally opposemovement of the cap relative to the tool head.

JAMES H. BLAIR.

